Question

What is reverse photoelectric effect?

Answer 1

We know that light exhibits dual nature, that is it can emit photons, and also shows properties of waves like in the case of the electromagnetic spectrum. This property of the light called dual nature was studied and there were two cases called the photoelectric effect of light and the other as the reverse photoelectric effect.

Complete answer:
The photoelectric effect and the reverse photoelectric effect of light also known as the Compton effect are complementary in nature as the name suggests.
In the photoelectric effect, when a beam of light was incident on a metal plate, it was found to emit electrons, which are commonly called the photoelectron. Here, the weakly bound electrons are emitted. This is used in the photomultipliers and night vision devices.
Whereas , in Compton effect, when an x-ray or gamma ray was bombarded onto a piece of material, the wavelength of the ray after bombardment was different, as the incident ray had given off a photon. Here, there is inelastic scattering of the photons. This shift in the wavelength of the incident and the observed wavelength is given by the famous equation called the Compton shift.

Note:
Since the photoelectric effect and Compton effect are complementary in nature, i.e. former, release photon due to incident ray , while the later produces a ray due to an incident charged particle. Since photoelectric effect was studied before the discovery of Compton effect, Compton effect is called as the reverse of photoelectric effect and not the other way around.